Industrial Training atPower grid corporation of india limited

(A Government of India Enterprises)

Presented By- Akriti Gupta Electronics and Communication Engg. 7th Sem 1409131905

ELECTRICAL SUBSTATION Electrical substation consists

of a number of incoming circuits and outgoing circuits connected to common busbar system. Busbars are conducting bars to which a number of incoming or outgoing circuits are connected.

A substation receives electrical power from generating station via incoming transmission lines and delivers electrical power via the outgoing transmission lines.

SLD of Substation

TRANSFORMER A transformer is an electrical device

that transfers electrical energy between two or more circuits through electromagnetic induction. Commonly, transformers are used to increase or decrease the voltages of alternating current in electric power applications.

Transformer is a static machine, which transforms the potential of alternating current at same frequency.

This substation has two types of transformer:-

-Two 165MVA 220/132kV transformers

- One 315MVA 400/220kV transformer

COOLING FANS Cooling fans are used for

forced air cooling of the transformer

165 MVA uses six cooling fans 315 MVA uses eight cooling

fans

All fans not start at the same time. They start in pairs.

CURRENT TRANSFORMER

In electrical engineering, a current transformer(CT) is used for measurements of electric currents.Current transformers, together with voltage transformers(VT)(potential transformers(PT)), are known as instrument transformers.

When current in a circuit is too high to

directly apply measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit,which can be conveniently connected to the measuring and the recording element.

CAPACITOR VOLTAGE TRANSFORMER A capacitor voltage transformer (CVT) is a

transformer used in power systems to step-down extra high voltage signals and provide low voltage signals either for measurement or to operate a protective relay.

In its most basic form the device consists of three parts: two capacitors across which the voltage signal is split, an inductive element used to tune the device to the supply frequency and a transformer used to isolate and further step-down the voltage for the instrumentation or protective relay.

CIRCUIT BREAKER A circuit is a automatically operate switch designed to protect the system

during shortcircuit or abnormal conditions. Below shown is of SF6 circuit breaker.

ISOLATORS In electrical engineering, a

disconnector, disconnect switch or isolator switch[1] is used to ensure that an electrical circuit is completely de-energized for service or maintenance.

Such switches are often found in electrical distribution and industrial applications, where machinery must have its source of driving power removed for adjustment or repair.

LIGHTNING ARRESTER Surges, or transients, are brief

overvoltage spikes or disturbances on a power waveform that can damage, degrade, or destroy electronic equipment within any home, commercial building, industrial, or manufacturing facility.

The overvoltage protection is obtained by the use of lightning/surge arresters.

Lightning Arresters or Surge Arresters are always connected in shunt to the equipment to be protected, they provide a low impedance path for the surge current to the ground.

Mostly in present days zinc oxide(Zno) gapless arresters are in use

RELAY In electrical engineering, a

protective relay is a device designed to trip a circuit breaker when a fault is detected.

The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, over-voltage, reverse power flow, over- and under- frequency.

Microprocessor-based digital protection relays now emulate the original devices, as well as providing types of protection and supervision impractical with electromechanical relays

WAVE TRAP Wave trap are used for

carrier communication. It traps the higher

frequency above 50 Hz. It is the effort to utilize

the same transmission line between to substation for the purpose of communication

WORKING

BATTERY ROOM The control panels and

relays of the substation require DC supply of 220 V. This DC supply is made with the help of battery bank reserve normally kept in a separate room called Battery room.

The batteries used in this substation are Nickel-Cadmium (Ni-Cd) batteries.

CONTROL AND RELAY ROOM

The control room has various control panels which shows the information like incoming power, outgoing power, frequency, time common to all substations, status of various lines (healthy, faulted, under outage or maintenance), status of various protective instruments like isolators, circuit breakers; temperatures of various instruments, working tap of transformers etc.

The relay room is separate from the control room. All relays used here are numerical and are either from Siemen ”OR ABB”.

The protection system is so fast that it can detect a fault within 30 ms and hence the circuit breaker can be operated within as less as 80 ms. For 400 kV side C.B.